Cairn Energy, the oil and gas producer, has seen revenues rise in the first half of 2011 from $333m last year to $1.3bn this year.The boost in revenues comes on the back of increased production which was up significantly on the same period in 2010, from 87,523 boepd (barrels of oil equivalent per day) to 166,527 boepd. Of that total, Cairn is entitled to revenues from 77,056 boepd.The strategic sale of some of its Indian interests to Vedanta Resources continues with $1.4bn already realised and a further $4bn to come, subject to approval from the Indian government and shareholders.The logic of the Indian sale has been to provide more cash for development of its wells in Rajasthan and exploration. Current exploratory operations in Greenland have not, so far, proved successful. Nevertheless the firm says it will continue to look for potential well sites using two rigs in the area.Commenting on the results Cairn's chief executive Simon Thomson said: "Cairn is encouraged that the Vedanta transaction is moving towards completion. Following approval from the Government of India, all parties are now working to satisfy the consents and conditions to complete the sale to Vedanta as soon as possible. The sale ... will allow a return of substantial funds to shareholders and will also provide the Group with the balance sheet strength and financial flexibility to explore new opportunities in line with its consistent strategy of seeking transformational growth."Cairn shares rose 1.5% in early trading.BS